Variable-power regulation.



J. A. SNEE, JR.

VARIABLE POWER REGULATION.

APPLICATION EILED FEB. 16, I915.

1,271,788. Patented Ju1y9,1918.

1- FIEIL CL Eli/e663 lfeloqziw WEE;

wrrmassszs JOHN A. SNEE, 53., OF WEST ELIZABETH, PENNSYLVANIA.

' VARIABLE-POWER REGULATION.

Specification of Letters Eatent.

Patented July e, 1918.

Application filed February 16, 1915. Serial No. $5,506.

manner as to maintain the wheel under the most eificient load regardlessof variations in the impelling current, the load increasing anddecreasing in approximately exact proportions to increase and decreaseoi maximum power which can be developed by the wheel in differentcurrent velocities.

The useful work done by a current wheel rises from zero at no speed to amaximum at the best or most efficient speed, and drops or recedes tozero at the runaway speed of the wheel. The best speed, 2'. 6., thewheel velocity that produces maximum power, depends upon the size anddesign of wheel a matter with which the present invention is notconcerned, the assumption being that the most eflicient speed for agiven wheel has been ascertained and the adjustments made in the lightof that knowledge.

When a current wheel is at its best speed for a given current velocity,it runs at a given speed, and it delivers a given amount of power. Whena wheel is developing maximum power for any current velocity, the torqueis approximately proportional to the square of such velocity, and theoutput of power is very nearly proportional to the cube of the windvelocity.

The foregoing mathematical facts well recognized in the art, are madeuse of herein 'to accomplish the desired regulation, two

opposing forces emanating from or set in motion by the current wheelbeing utilized in such manner that oneso counteracts the other as tomaintain a substantially uniform relation between the load of the wheeland the velocity of the variable impelling wind or water current. One ofthese governing forces is derived from the torque, or output of powerresulting from the operation of the wheel, and this force is utilized toreduce the output of the wheel or the machine driven by it. The othergovernin force, which opposes the first mentioned orce, is

' and of derived from the speed of the current wheel or speed of themachine driven by it. This second force is so utilized as to increasethe output of the wheel or of the driven machine. The relation of thissecond force to the speed depends upon the first or outputreducingforce; that is to say, it must vary in the same power of the speed asthe force which tends to reduce the output. These two opposing forceswill balance'each other at some speed and output, and in pursuance ofthe present invention the speed and outputare so related that the effectof the opposing governing forces is to always maintain the current wheelat its best speed. And while the speed will be diflerent in d-ifi'erentcurrent velocities it willalways be that speed that will produce maximumout-.

put of work or power from the prevailing current. Having thusascertained that relation which causes the two opposing regulatingforces to vary as the identical function or power of the speed, itremains to so adjust the intensity of one of said,forces as to cause theoverning forces to always ap' proximately alance each other at the bestspeed of the wheel.

The principles underlying the invention may be applied by apparatus ofmany forms widely varying construction. Only one of the embodiments isillustrated in the accompanying drawings.

In the drawings, Figure 1 is a diagram illustrating load curves fordifferent current velocities. Fig. 2 is 'a diagrammatic View ofapparatus wherein one of the forces is derived from the torque of thedriven machine and the other regulating force is derived from the speedof such machine, the opposing forces being here shown as controlling aresistance in a generator field in such manner that the work performedby the machine is substantially proportional to the cube of the velocityof the impelling current.

In the diagram, Fig. 1, work or output of power represented by verticalline ab is plotted against wheel velocity indicated by horizontal linew-0. The parabolic curves A represent work or output of a wheel, orwheel-driven machine, for as many different current velocities. Theupwardly curved line a-d, which intersects the highest portion of eachcurve A, is the line of maximum power which is maintained by means'ofthe present invention.

Point at designates no current velocity, and

point cl maximum current velocity. As the highest part of each curve A.is substantially flat, slight departure from the best speed will notnoticeably afiect the efficiency. If the wheel velocity for anyimpelling current wereto exceed that which is necessary to carry theoutput to line a-d, i. 6., the output of maximum efficiency, the powerwould decrease with increase of excess speed, and if the excess weresufficiently great the power development would return to zero, asindicated by the descent of curves A from the right hand side of linead.

In the apparatus shown in Fi 2, the load imposed upon the current wheeby a shuntwound electric generator is so automatically regulated as tomaintain the wheel at its most efiicient power-developing speed for anyand all wheel-impelling currents of sufficient velocity to do usefulwork; In this adaptation, one of the governing forces is derived fromthe torque of the generator, and the other and opposing force from thespeed of the current wheel. Referring to said view, 2 designates a wheeladapted to be driven by a changeable or variable current, such as windor water. 3 is the rotor of an electric generator which is geared towheel 2 (in the conventional illustration by means of belt 4), and 5 isthe generator stator. The generator is shunt wound, and in series withits field 6 is a variable resistance 7 here shown of carbon-pile type.In series with the generator leads 8 may be consumers and storers ofelectric energy of various forms, for instance lamp circuits 9, heatingcoil 10 or storage battery 11.

Stator 5 is unstable, being mounted to 0s cillate in housing 23 onroller bearings 24 or other friction preventing devices. Projecting fromone side of the stator is arm 12 carrying an adjustable weight 13, andfrom the opposite side arm 14 provided with a similar weight 15. Arm 12cooperates with resistance 7, depression of the arm compressing theresistance and increasing the 'current flow through the field andcorrespondingly increasing the load, while upward movement of arm 12results in expansion" of the resistance which correspondingly de creasesthe current flow, with a proportional decrease of load. The elevation ofarm 12 is induced by the torque of rotor 3, the amount of torqueincreasing as the speed increases, with corresponding decrease ofcurrent flow through field 6. The force which opposes the torque istransmitted to the stator through arm 14, and may emanate from acentrifugal pump 16 which is geared at 17 to rotor 3, the pump, however,simply acting as a pressure producer in forcing fluid from container 18into cylinder .19

where the pressure is exerted on piston 20.

I which is connected by pitman 21 to arm 14. The pitman may have asliding connection with said arm as shown, so thatby moving the pump toeither the right or the left, the leverage may be decreased or increasedfor first adjustment. The pump discharge may be choked at 22 and therebycause the cylinder and piston to operate as a dash-pot, preventingsurging of stator 5. As it is well understood that the pressure producedby a centrifugal pump against a closed discharge is proportional to thesquare of the speed, such apparatus regulates the torque, keeping itproportional to the squareof thespeed, thereby providing exactly theforce relation herein desired.

Operation: As the available power of a current wheel increases with thecube of' the current velocity and as its torque for maximum outputincreases with the square of such velocity, the desired regulation isaccomplished and the wheel is maintalned at its best or most eflicientspeed regardless of the current velocity within reasonable limits,althoughit will be understood that, as in the ease of a wind wheelsubjected to a too high wind, means well known in the art may beutilized for turning the wheel out of the wind. The controlling forcederived from the speed and made effective by pump 16 opposes the forcederived from the torque of rotor 2, and the counteraction of each ofsaid forces on the other is such, in view of the mathematical lawsherein observed, that the generator at all times imposes a load on thewheel which is proportional to the cube of the wind velocity, and thisnecessarily results in maintaining the wheel at its most efiicientpower-developing speed. Increase of speed increases the force exertedby'pump 16, causing that force to dominate the force derived from thetorque, and the resulting compression of resistance 7 increases thecurrent fiow through the field with corresponding increase ingeneratorload imposed upon the wheel, and the slowing down of the latterdecreases the pump pressure until the opposed governing forces are againin balance. Similarly, if the loadis decreased, as by cutting out one ormore of the consuming devices, the tendency to increase the speed underthe lighter load puts the governing forces at once in action and theequilibrium is restored. Weights 13 and 15 are useful in making theinitial adjustments,

and it Will be understood that resistance 7 as well as other parts ofthe controlling which is a function of the speed of such motor, anotherforce which is a function of the torque thereof, and in balancing saidforces against each other and regulating the load on the fluid motor inaccordance with the point of balance, so'that the motor is maintained ata predetermined speed for each fluid velocity.

2. The method of speed control of a fluid motor operating under varyingfluid velocities, which consists in producing a force which isproportional to the square of the motor velocity and a force which isproportional to the torque of the motor, in balancing said forcesagainst each other and regulating the load on the fluid motor inaccordance with the point of balance so that the motor is malntained ata predetermined speed for each fluid velocity and in utilizing anyunbalance in said forces to vary the motor load, increasing the' load asthe motor speed exceeds a predetermined speed and 'decreasing speed.

3. The method of speed control of a fluid motor adapted to operate withvarying fluid velocities, which consists in producing a centrifugalforce which is proportional to the square ofthe motor velocity and aforce which is proportional to the torque of the motor, and balancingsaid forces against each other so that when the balance is the load asit falls below such reached for any particular fluid velocity, the,

motor runs at a predetermined speed, and in utilizing any preponderanceof said first force over said second force to increase the motor loadand vice versa.

In testimony whereof I afliX in presence of two witnesses,

JOHN A. SNEE, JR.

my signature Witnesses:

WM. A. Poem, F. J. KERRIGAN.

